Lactate and acid-base balance at delivery in relation to cardiotocography and T/QRS ratios in the second stage of labour.
OBJECTIVE
To compare foetal electrocardiogram (T/QRS ratio) and cardiotocography (CTG) during the second stage of labour with lactate and acid-base balance in cord artery blood at delivery.


METHODS
Forty-six parturients delivered at the National University of Singapore were monitored during the second stage of labour with T/QRS ratios and CTG. At delivery blood from a segment of clamped cord was sampled for lactate and acid-base balance analyses. The Spearman Rank correlation, the Mann Whitney U-test and the Kruskal Wallis ANOVA were used when appropriate.


RESULTS
Maternal pushing time was significantly correlated to lactate (R = 0.51; P = 0.0003), pH (R = -0.38; P = 0.009) and base deficit (R = 0.33; P = 0.026), but not to T/QRS ratio (R = 0.002; P = 0.99). No significant correlation between lactate and T/QRS ratios (R = 0.06; P = 0.70) or type of CTG pattern was found (P = 0.10), though there were significant differences in pH (P = 0.029) and T/QRS ratios (P = 0.037) between groups with different FHR abnormalities.


CONCLUSIONS
Lactate increases progressively with maternal pushing time. No significant correlation was found between lactate and the T/QRS ratio. Lack of correlation is likely to be due to poor sensitivity of foetal ECG at this level of foetal stress, though the influence from transplacentally transferred maternal lactate cannot be excluded.
Nordström
L
L
Department of Obstetrics, National University Hospital, Singapore.
Malcus
P
P
Chua
S
S
Shimojo
N
N
Arulkumaran
S
S
D000136:Acid-Base Equilibrium; D015148:Cardiotocography; D004562:Electrocardiography; D005260:Female; D005312:Fetal Blood; D006340:Heart Rate, Fetal; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007748:Labor Stage, Second; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D011247:Pregnancy; D014469:Umbilical Arteries
D019344:Lactic Acid